scholarly journals Engineering Practice of Ultra-high Pressure Hydraulic Slotting and Pressure Relief Pumping in Through Layer Hole

2021 ◽  
Vol 236 ◽  
pp. 01029
Author(s):  
Siqian Li
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
High Efficiency ◽  
Engineering Practice ◽  
Pressure Relief ◽  
Gas Drainage ◽  
Thick Coal Seam ◽  
Ultra High Pressure ◽  
Drainage Rate ◽  
Gas Control

In order to solve the problems of low gas drainage rate and long drainage time in thick coal seam with low permeability, ultra-high pressure hydraulic slotting pressure relief and permeability enhancement technology was applied in the test. The practice shows that after adopting the ultra-high pressure hydraulic slotting, the gas drainage rate is greatly improved, the time for reaching the standard of drainage is shortened, and the difficult problem of gas control in the mining face of thick coal seam is solved, which provides technical guidance for high-efficiency gas control in thick coal seam with similar conditions in mining area.

scholarly journals Reasonable Arrangement of High-Level Orientation Extraction Boreholes of Pressure Relief Gas in Overlying Strata under High-Strength Fully Mechanized Mining in Low-Gas-Thick-Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Han Gao ◽  
Xuanping Gong ◽  
Xiaoyu Cheng ◽  
Rui Yu ◽  
Hui Wang
Keyword(s):  
Coal Seam ◽  
Gas Flow ◽  
High Strength ◽  
Distribution Characteristics ◽  
Pressure Relief ◽  
Gas Field ◽  
Thick Coal Seam ◽  
Gas Accumulation ◽  
Working Face ◽  
Gas Control

In order to solve the problem of pressure relief gas control under high-strength fully mechanized top-coal caving in low-gas-thick-coal seams, this paper studies the evolution of overburden structures and the distribution characteristics of fissure fields during the initial and stable period of working face by physical simulation and numerical analysis. The mathematical model of coupling between mining fracture field and pressure relief gas field is established. The results reveal the distribution characteristics of pressure relief gas field that considers mining-induced fissure field. According to the distribution of mining gas accumulation area, the high directional long boreholes have been put forward to control the pressure relief gas in goafs, and the effect has been tested. The results show that the initial pressure and three periodic pressures occurred from the cutting hole to 135 m in the initial mining period of the working face. The height of collapse zone developed to 22 m, and fracture height developed to 75 m. The development height of caving zone is stable at 25∼27 m, and the development height of fissure zone is stable at 75∼95 m. The process and distribution of pressure relief gas flow in goaf are obtained by solving the numerical model of pressure relief gas flow in mining fissure field. The gas accumulation area is located within 25∼55 m from return laneway and 25∼50 m from the roof of coal seam. After the implementation of high directional long drilling gas drainage technology in the initial mining period and the stable mining period, good results have been obtained in the gas control, where the average concentration of gas extraction is 5.8%, the average gas flow rate is 0.71 m3/min, and the gas concentration in upper corner and return air is less than 0.8%. The results can provide a reference for pressure relief gas control under similar conditions.

scholarly journals Research on the Coal Seam Permeability-Increasing Technology via High-Pressure Water Jet Reaming and Its Application

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Xingang Niu ◽  
Biming Shi ◽  
Zhigang Zhang ◽  
Yongjiang Zhang
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
Water Jet ◽  
Pulverized Coal ◽  
Gas Drainage ◽  
Drainage Volume ◽  
Single Hole ◽  
Drainage Rate ◽  
Pressure Water ◽  
Conventional Drilling

Aiming at the problem of coal and gas outburst prevention and control in serious outburst dangerous coal seam under complex geological conditions in Qidong Coal Mine, the water jet drilling and expanding integrated device was used to implement the measures that expand holes and increase permeability by high-pressure water at a 912 working face. The experimental results show that when the pump pressure is between 13 MPa and 15 MPa, the particle size of pulverized coal can be effectively reduced and the discharge of pulverized coal can be increased. The coal output of a single hole is 0.8~2.3 t/m, with an average of 1.1 m/t. The unreamed conventional borehole has a single-hole initial gas drainage rate of 50.74 m3/d and a single-hole cumulative gas drainage rate of 736.12 m3 within 30 days. The initial single-hole gas drainage volume of the reaming borehole is 178.74 m3/d, and the cumulative single-hole gas drainage volume in 30 days is 2227.57 m3. After reaming, the initial gas drainage scalar of a single hole increases 3.52 times of the original unreamed conventional drilling and the average cumulative gas drainage scalar of a single hole reaches 3.03 times of the original unreamed conventional drilling. This technology and equipment have a good promotion and application value in gas treatment of soft, low-permeable coal seams.

Gas drainage technology of high gas and thick coal seam

2009 ◽  
Vol 15 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Tian-cai He ◽  
Hai-gui Li ◽  
Hai-jun Zhang
Keyword(s):  
Coal Seam ◽  
Gas Drainage ◽  
Thick Coal Seam

scholarly journals Permeability Enhancement Properties of High-Pressure Abrasive Water Jet Flushing and Its Application in a Soft Coal Seam

2021 ◽  
Vol 9 ◽  
Author(s):  
Xinzhe Zhang ◽  
Piotr Wiśniewski ◽  
Sławomir Dykas ◽  
Guojie Zhang
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
Water Jet ◽  
Gas Pressure ◽  
Theory And Practice ◽  
Abrasive Water Jet ◽  
Gas Drainage ◽  
Permeability Enhancement ◽  
Soft Coal ◽  
Soft Coal Seam

High-pressure abrasive water jet flushing (HPAWJF) is an effective method used to improve coal seam permeability. In this study, based on the theories of gas flow and coal deformation, a coupled gas-rock model is established to investigate realistic failure processes by introducing equations for the evolution of mesoscopic element damage along with coal mass deformation. Numerical simulation of the failure and pressure relief processes is carried out under different coal seam permeability and flushing length conditions. Distributions of the seepage and gas pressure fields of the realistic failure process are analyzed. The effects of flushing permeability enhancement in a soft coal seam on the gas drainage from boreholes are revealed by conducting a field experiment. Conclusions can be extracted that the gas pressure of the slotted soft coal seam is reduced and that the gas drainage volume is three times higher than that of a conventional borehole. Field tests demonstrate that the gas drainage effect of the soft coal seam is significantly improved and that tunneling speed is nearly doubled. The results obtained from this study can provide guidance to gas drainage in soft coal seams regarding the theory and practice application of the HPAWJF method.

Computational fluid dynamics optimization of gas drainage technology in gas-mining areas

2021 ◽  
pp. 014459872110635
Author(s):  
Wei Zhao ◽  
Wei Qin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Coal Seam ◽  
Field Tests ◽  
Mining Area ◽  
Engineering Practice ◽  
Horizontal Distance ◽  
Gas Drainage ◽  
Working Face ◽  
Gas Seepage

Coal mining results in strata movement and surrounding rock failure. Eventually, manual mining space will be occupied by the destructed coal rock, making it difficult to conduct field tests of the coal seam to explore gas seepage and transport patterns. Therefore, computational fluid dynamics (CFD) numerical computation is an important tool for such studies. From the aspect of gas pre-drainage, for layer-through boreholes in the floor roadway of the 8,406 working face in Yangquan Mine 5 in China, reasonable layout parameters were obtained by CFD optimization. For effectively controlling the scope of boreholes along coal seam 9 in the Kaiyuan Mine, CFD computation was performed. The results revealed that the horizontal spacing between boreholes should be ≤2 m when a tri-quincuncial borehole layout is used. Optimization of the surface well position layout for the fault structure zone in the Xinjing Mine of the Yangquan mining area indicated that the horizontal distance between the surface well and the fault plane should be <150 m. From the aspect of gas drainage with mining-induced pressure relief, CFD computation was performed for pressure-relieved gas transport in the K8205 working face of Yangquan Mine 3. The results showed that forced roof caving should be used before the overhang length of hard roof reaches 25 m in the K8205 working face to avoid gas overrun. From the aspect of gas drainage from the abandoned gob, surface well control scopes at different surface well positions were computed, and an O-ring fissure zone is proposed as a reasonable scope for the surface well layout. CFD computation has been widely applied to coal and gas co-extraction in the Yangquan mining area and has played a significant role in guiding related gas drainage engineering practice.

scholarly journals Development of Ultra-high Pressure Cooling and Quick Freezing Device Based on Hydraulic Transmission

2019 ◽  
Vol 118 ◽  
pp. 02032
Author(s):  
Min Li ◽  
Changming Ling ◽  
Biao Ye ◽  
Junhao Cai ◽  
Wenzhen Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Energy Consumption ◽  
Pressure Relief ◽  
Ultra High Pressure ◽  
Whole Process ◽  
System Pressure ◽  
Transmission Design ◽  
Quick Freezing ◽  
Feeding Pressure ◽  
Continuous Work

Based on the theory of high pressure supercooling and pressure relief quick freezing, the ultra-high pressure instantaneous freezing device is developed. This device can break through the limitations of existing ultra-high pressure device design. Through the new hydraulic transmission design, It can complete fast pressurization, fast pressure relief and achieve continuous work. The matching of whole systems under certain load conditions, hydraulic transmission system, refrigeration system, pressure vessel and pressure relief system has been completed. The device can realize the whole process of ultra-high pressure quick freezing from food feeding, pressure cooling, pressure relief instant freezing and semi-automatic food discharging. Compared with the conventional same-capacity quick-freezing device, the energy consumption of the instantaneous freezing device under the design condition is only 24.52% of that of the traditional quick-freezing device, which greatly saves energy consumption. From the perspective of application, the design concept of ultra-high pressure quick-freezing device is perfected and the practical process of ultra-high pressure quick-freezing is advanced.

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